1. Field of the Invention
The present invention relates to a steam trap, particularly to a steam trap which is operated by electric conduction of the condensate generated and thus named as electric conductive type steam trap.
2. Brief Description of the Prior Art
In the conventional factories using steam as the heat transferring medium, the high pressure and high temperature steam generated by the steam boiler will condense after heat-exchange. The drain or condensate stored in the end portion of the steam pipes must be discharged properly not to influence the efficiency of heat-exchange and not to discharge live steam. Therefore, several kinds of steam traps have been developed in the past.
The conventional steam traps are mechanical type ones such as thermodynamic steam traps and float steam traps shown in FIGS. 1 and 2. The thermodynamic steam trap is very simple in structure, however, the operation mechanism thereof is not perfectly understood. The flash steam passes the disc 10 in a relatively high speed, and the pressure difference generated by the floating steam will activate the disc 10 to close the exit of the condensate. This kind of thermodynamic steam trap is only available to discharge the condensate of a temperature lower than the steam by 2 to 3 degrees centigrade. Besides, the trap will be out of function if a large amount of gas is introduced into the pipes.
The float steam trap shown in FIG. 2 controls the operation of a valve 21 by the floating mechanism of the floating bulb 20. Therefore, this kind of steam trap is used at the place where pressure or load changes frequently and is able to discharge the condensate of the same temperature as the steam. However, the principal disadvantage of the float steam trap is that it will be easily damaged by water hammering.
Except the disadvantages of the conventional steam traps stated hereinabove, there are still a number of common disadvantages such as: the temperature range of application is limited and so is the pressure range, the frequency for discharging the condensate is rather high causing the high pressure steam in the pipe to leakage and a lot of heat energy lost, the mechanical structure is complicate causing a high maintenance cost, a short life time, etc.